Did Upright Walking Start in Trees?

I remember reading somewhere that walking up right had no evolutionary advantage, and I remember thinking at the time, that it was not necessarily true. When one reads about our ancestors having migrated from Africa, and evidence is found as far away as Northern Asia? Then one could think of this as evidence of there migratory powers. Then one could be led to think, that walking up right enabling them to migrate in search of food and water, thous having an effect on our ancestor evolution? Drought and famine could then be put forward as the reason for the evolution?

I have read of some research that suggests we partly evolved on and around shorelines. This would explain our upright stance and lack of body hair, and also one the the biggest puzzles still unexplained, where did we get the essential fatty acids necessary for the development of our big brains. (Available in sea food) It also explains why we have 10 times the number of fat cells compared to our simian cousins, and our predilection for beach side property. I think this is a stronger argument then the treetops.